1. Field of the Invention
The present invention relates to an image formation unit integrally mounting a plurality of replaceable members and detachable from an image forming apparatus, an image forming apparatus that employs the image formation unit, and a method of recycling the image formation unit.
2. Discussion of the Background Art
In an image forming apparatus, a process cartridge integrally mounting one or more replaceable members, such as a photoconductive drum, a developing device, a charging device, a cleaning device, etc., is sometimes employed to readily perform their maintenance. The process cartridge is monitored to replace with a new process cartridge at an appropriate time, because an image deteriorates as the process cartridge approaches a usage limit. For example, the process cartridge is replaced when end of the life is supposed based upon an accumulated number of image formations stored in a memory of the image forming apparatus. However, an accumulated number of image formations cannot be known in such a method when a process cartridge is replaced with a new process cartridge. Thus, the accumulated number of images is necessarily written on a memo when the process cartridge is replaced.
Then, an image forming apparatus is proposed such that an accumulated number of image formations is stored in a non-volatile memory arranged in a process cartridge, while a usage limiting number of image formations is stored in a memory of an image forming apparatus, as discussed in Japanese Patent Application Laid Open No. 2002-182532. Such an image forming apparatus recognizes the end of life of the process cartridge and stops image formation when the accumulated number of images exceeds the usage limiting number of image formations. According to such an image forming apparatus, making memo is needless, because the accumulated number of image formations is stored in the nonvolatile memory. However, a replaceable member to be replaced is unknown when a process cartridge includes a plurality of replacement members.
Further, an image forming apparatus is proposed such that a life of a process cartridge is converted into a number of rotations of a photoconductive drum and the number is stored in a nonvolatile memory provided in the process cartridge. A number of practical rotations of the photoconductive drum is retained. A control section arranged in the image forming apparatus compares both numbers and recognizes a life thereof. Further, another method is proposed such that a replacement member is replaced when a number of recycling times of a photoconductive drum reaches a prescribed level, as discussed in Japanese Patent Application Laid Open No. 2000-347550. Thus, are placeable member to replace can be known.
However, information of a replaceable member newly installed in the process cartridge during recycling is not stored. Thus, a life of the newly installed replaceable member cannot be recognized. As a result, quality and credibility of a recycled process cartridge cannot be guaranteed.